FR2487570A1 - Compressed gas circuit breaker - has resistance arranged as stack of cylindrical discs to be inserted during closing of switch - Google Patents

Abstract

The circuit breaker includes a ceramic insulating envelope with a plate providing support for a tubular contact carrier. The plate also acts as support for a resistance in a housing, formed either of pure aluminium or alloy. The tubular housing ends with flanges. A cap of conducting material is attached to the upper flange. The resistance formed of a stack of cylindrical discs, is placed in an insulating cylinder which is resistant to attack from the decomposition produces of the surrounding gas. A spring placed on a guide attached to the cap, presses on a plate to compress the discs to ensure a good contact between them. A braid shunts the spring, and an insulating washer is positioned between the spring and the plate to prevent a flow of current through the spring.

Description

Compressed gas circuit breaker
The invention relates to a compressed gas circuit breaker, and more particularly to a circuit breaker comprising a device for inserting resistance to closing only.

 It is known to use resistors to reduce the overvoltages that can occur in very high voltage networks during closing or reclosing on a long line that remains charged by the cut of the capacitive current.

 The value of such a resistance must be close to that of the wave impedance of the line. But a resistance insertion duration, which varies with the networks is an interesting point and a circuit breaker is more flexible, it adapts without much change to shorter or longer insertion times.

 To obtain this result, resistors put into service and out of service are used in an auxiliary chamber controlled by independent operating members or at least adjustable relative to the operating member of the main chamber of the circuit breaker. But this leads to bulky and more expensive devices having two chambers and two actuators.

 If we place the two main and auxiliary rooms, in the same envelope, it is very bulky.

 In the case of a compressed gas actuator, it is possible by nozzles, dead volumes, to adjust the delay of the main chamber relative to the auxiliary chamber, and consequently to regulate the duration of 'insertion. If the operating member is mechanical, as is generally the case for sulfur hexafluoride circuit breakers of the self-compression type, it is necessary to have two operating members if the resistance is not to be trip circuit.

 The object of the invention is to produce a compressed gas circuit breaker with a device for inserting a resistance to single closing, with a single operating member and of reduced bulk.

 The subject of the invention is a compressed gas circuit breaker comprising a fixed tubular contact, a movable tubular contact, a resistance insertion device when it is closed only, the insertion devices and the resistance being arranged in a coaxial envelope, said device being controlled by the movable contact of the circuit breaker, characterized in that the insertion device is of the semi-mobile type and comprises a first means for damping its closing and a second means for delaying its opening when the circuit breaker opens.

 According to certain characteristics, the first means and the second means are of the vacuum-operated type. The first means comprises a means for adjusting the spacing between a semi-mobile contact for inserting the insertion device and a mobile contact for inserting the mobile contact, said insertion device being subjected to the antagonistic action of a spring acting in the opening direction.

 According to other characteristics, the circuit breaker includes a spark arrester contact arranged coaxially with the fixed main and movable main contacts. The spark arrester contact is subject to the fixed contact by means of a support with three radial arms in the interval of which three beams are arranged supporting the semi-mobile insertion contact.

 The resistor can be constituted by a central battery arranged in series with several peripheral batteries connected in parallel.

The linear resistance of all the peripheral cells is equal to that of the central cell.

 The characteristics and advantages of the invention will emerge from the description of an embodiment, given by way of example and illustrated in the drawing.

 Figure 1 shows a partial schematic view in partial section of a circuit breaker according to the invention in the open position.

 FIG. 2 is a partial schematic view on a larger scale of the lower part of the circuit breaker according to FIG. 1 along section II-II of FIG. 3.

 Figure 3 is a partial schematic sectional view of the circuit breaker according to Figure 2 along III-III.

 Figure 4 is a partial schematic view of the circuit breaker according to Figure 2 in the closed position.

 Figure 5 is a schematic view of the upper part of the circuit breaker showing an alternative embodiment of the closing resistance.

 In the figures, the insulating envelope, for example made of ceramic, of a circuit breaker with sulfur hexafluoride self-compression and mechanical transmission of its movement has been designated by 1. The insulating envelope 1 is closed at the lower end by a casing, not shown, which contains the jacks or mechanical movement transmission devices. The upper end comprises a collar 2, a plate 3 carrying a terminal 3 'for external connection.

 On the plate 3, a fixed tubular main contact port 5 has been fixed to the lower part, and in a leaktight manner to the upper part, a tubular casing 4 containing a resistance, the assembly of which is marked by 8, the elements 4 and 5 being advantageously assembled before mounting in the casing 1 The casing, which is metallic, for example made of pure or alloy aluminum, ends with flanges 6 and 6 '. On the flange 6 'is mounted a cover 7 made of conductive material. The resistor 8 which, formed of stacked cylindrical wafers, is placed in an insulating cylinder 9 insensitive to the decomposition products of sulfur hexafluoride. A spring 10 placed around a guide 11 secured to the cover 7 is supported on a plate 12 which compresses the wafers of the resistor 8 and thus ensures good contact therebetween. A braid 13 shunts the spring, and an insulating washer 14 is interposed between the spring 10 and the plate 12 in order to avoid the passage of current in the spring. The spring 10 is compressed during the assembly of the tube 9 by means of bolts 15 on a shoulder 16 of the cover 7. It is thus possible to make the casing 4 and the insulating cylinder 9 strictly coaxial.

 The lower end of the cylinder 9, which is frustoconical, is closed by a frustoconical endpiece 17 having a central shoulder which supports a guide rod 18 on which slides a semi-mobile insertion device 19 carrying on its lower end a contact d tubular insertion 20 of the resistor 8.

 The upper fixed contact comprises the contact carrier supporting on the one hand in its extension of the main contact fingers such as 22 distributed on its periphery and on the other hand transversely by three radial arms 60 a support 23 on which is fixed coaxially in the center a conductive tube 21, the end of which consists of a spark arrester contact 29.

 The tubular insertion contact 20 is connected to the device 19 by three longitudinal members 61 arranged in the interval separating the three radial arms 60, and obtained, for example, by longitudinal cutting of the tube constituting the contact 20.

 The movable contact of the circuit breaker comprises a hollow movable contact tube 30, used for the passage of ionized gases during cutting, pulled towards the arm or pushed upwards by a device not shown and housed in a casing. It further comprises a lower mobile contact holder 31 fixed on the tube 30 and concentrically supporting the mobile main contact 32, in the form of a crown, from the periphery towards the center, a mobile insertion contact 62 in the form of a ring, a nozzle blower 33, movable spark arrester contact fingers 34.

 A fixed piston 35 cooperates with a blowing cylinder 36 integral with the movable contact carrier 31. The casing 1 is filled with sulfur hexafluoride under a pressure of the order of three bars.

 The upper fixed contact carrier 5 has the form of a perforated conductive tube and in fact having at each end a short cylindrical collar 26 and 27 connected together by six bars 28 and obtained, for example, by longitudinal cutting of this conductive tube.

 The upper flange 26 allows connection to the plate 3.

The lower flange 27 is connected on the one hand to a contact carrier 24 of revolution and on the other hand to the arms 60 of the support 23, which has very rounded shapes inwards. On this support 23 is screwed the tube 21. The main fixed contact is constituted by fingers 22 held on their periphery by springs 25, the movement of the fingers 22 towards the center of the chamber being limited by a tubular contact carrier 24. These fingers are made of copper flat with a curved part at the end in order to obtain good guidance when coming into contact with the movable main contact 32.

 A damping device 40 is fixed on the metal end piece 17 closing the insulating cylinder 9, the body of which has a central bore 44 terminated by a groove 45 into which open side vents 46 distributed, on the periphery of the groove 45.

 The guide rod 18 has a circular shoulder 47 which makes it possible to clamp together a circular diaphragm 41 pierced with holes 42, a flexible rubber seal 48 and a ring 49 for immobilizing the seal 48.

 The flexible seal 48 normally closes the holes 42 of the diaphragm 41 to form a valve. The insertion device 19 slides on the guide rod 18.

 The insertion device 19 has at its upper end a male part constituted by a collar 50 of diameter corresponding to the bore 44 and a female part constituted by a bell 51 which cooperates with a nut 52 fixed at the end of the guide rod 18; washers 53 stacked make it possible to adjust the position of the nut 52 relative to the body of the damping device.

 In its movement along the rod 18 the insertion device 19 is guided by a rigid rod 54 secured to the body of the damping device 40 and passing through a notch in the base of the bell 51. A spring 55 bearing on the periphery of the body of the damping device 40 normally pushes the insertion device 19 against the nut 52 or in the direction of the nut 52 according to its position.

The circuit breaker works as follows
In the closed circuit breaker position, represented in FIG. 4, the current passes successively through the parts 3, 5, 27, 24, 22, 32, 31.30.

 In the open circuit breaker position, shown in FIGS. 1 and 2, the voltage is applied between on the one hand the main movable contact 32 and the spark arrester 34, and on the other hand the spark arrester contact 29 and the contact 20 d insertion, the shortest distance being that separating the movable insertion contact 62 and the insertion contact 20.

 When closing, in its movement from bottom to top, according to arrow F in FIG. 2, the main movable contact comes into contact with the insertion contact 20 after a possible pre-ignition before the spark arrester contacts 34 and 29 do not touch, as shown in dashes on the right side of Figure 2.

 The semi-movable insertion contact 20 is then pushed upwards against the action of the spring 55, but there is no rebound between the contacts 20 and 32 thanks to vacuum damping produced by the sliding of the bell 51 on the nut 52, the gas penetrating between the two parts 52 and 51 by the clearance left between them. From the galvanic contact between the contacts 62 and 20, or from the moment of the pre-ignition if it takes place, the resistance 8 is crossed by the current which successively borrows the elements 62, 20, 51, 56, 54, 40, 17, 8, 12, 13, 7, X, 6, 3, the part 56 constituting a wiper interposed between the bell 51 and the rod 54. The voltage corresponding to the voltage drop in the resistor 8 is applied between a share the elements 22, 5, 6, the bars 28 of the contact holder 5, the support 2 the tube 21, the spark arrester contact 29, and on the other hand the side members 61 of the insertion contact 20 as well as on the elements of the mobile contact. To be able to withstand the tension, the facing pieces have rounded shapes in order to improve the distribution of the electric field and the side members 61 and the insertion contact 20 have a minimum thickness.

 Continuing its upward movement, the movable spark arrester contact 34 touches the fixed spark arrester 29 and, at this instant or at the instant of pre-ignition between these two parts if the voltage across the resistance is not zero, the resistor 8 is shunted the current passing through the parts 34, 29, 21, 23, 5 6, 3, the path of which is very little resistant; the current is definitively established in the circuit breaker. At the end of the stroke, the main movable contact 32 comes into contact with the fingers 22, the collar 50 penetrates into the bore 44, the damping is low since the gas which is compressed escapes through the holes 42 of the diaphragm 41, released from the seal 48 pushed back and forming a valve, as well as by the vents 46.

 The insertion time can be adjusted and increased by adding washers 53 which move the nut 52 downwards, therefore by the same distance the part 20, without changing the kinematics or the speed of movement of the moving contact crew.

 When the circuit breaker opens, the moving contact assembly moves in the opposite direction, that is to say from top to bottom. There is first an abrupt separation, of the insertion contact 20 and the movable contact 62, then of the main contacts 22 and 32. The displacement from top to bottom of the contact 20 is obtained by the action of the spring 55 on the device insertion 19, but the speed is very low at the start, because the diaphragm 41 and the seal 48 function as a valve, the gas penetrating only thanks to the clearance between the collar 50 and the bore 44 on the one hand and negligible leakage at the joint 48.

 The separation of the contacts of the circuit breaker ends between the spark arrester contacts 34 and 29, and at this instant the distance between the contacts 20 and 62 is sufficient to avoid any re-ignition between on the one hand the contacts 20 and 22 and on the other hand share the movable contacts 32 and 62. The movement of the insertion device 19 and of the contact 20 accelerates after exiting the collar 50 from the bore 44 of the body of the damping device 40, then is damped when the bell 51 surrounds the nuts 52.

The clearances and the damping lengths at nut 52 ensure
the absence of rebound during the impact of the movable contact 62 against the insertion contact 20 when closing,
- a rest position of the bell 51 on the nut 52 after 0.1 to 0.2 seconds, so that the insertion contacts are in place, ready for reclosing according to an opening and closing cycle with a isolation time in a total duration of about 0.2 to 0.3 seconds. The nut 52 has a rounded shape so as to improve the damping and to favor the release of the ionized gases produced by the arc and blown by the compressed gas in the cylinder 36 escaping through the tubes 21 and 30 during the opening. .

The advantages of the circuit breaker are as follows:
The breaking chamber of the circuit breaker, the resistor and its insertion device are arranged in the same enclosure.

 Thanks to the addition or removal of shims or washers 53 it is possible to adjust the instant of the insertion of the resistance and its duration.

 Bouncing of the insertion contact, which would cause an arc damaging the contacts and could cause transient electrical phenomena, is avoided.

 The variant embodiment of FIG. 5 allows a reduction in the height of the upper part of the circuit breaker.

Resistor 8 is then produced using several insulating tubes:
- A central tube 89 similar to that of the tube 9 of Figure 1, but shorter than the latter, is supported on a conductive plate 90 resting on four peripheral insulating tubes 91 of inner section equal substantially to a quarter of the inner section of the tube 89.

Each of these tubes contains a stack of resistors 92 with a diameter half that of the central cell 80. The four resistance batteries 92 of the tubes 91 therefore have the same linear resistance as the central resistance 80. The four tubes 91 are fixed on the tray 3; a cover 93 closes tightly and envelops the tubes 91 and 89.

 Spring devices similar to those shown in Figure 1 maintain contact between the resistant discs and electrical continuity; the current thus passes through elements 8, 90, 92 and 3.

The advantages of this arrangement are as follows:
- The cover 93 is not traversed by the current.

 - The part containing the resistor is shorter with a larger diameter, but which generally fits into the dimensions of the insulating envelope 1.

 Instead of having four peripheral resistors around the central resistance, a different number could be available, for example three, but of equivalent total section.

 It is obvious that the invention is in no way limited to the embodiment which has just been described and shown and which has been given only by way of example; in particular, without departing from the scope of the invention, it is possible to modify certain provisions or replace certain means by equivalent means, or else replace certain elements by others capable of ensuring the same function or an equivalent technical function.

Claims (6)

1 / Compressed gas circuit breaker comprising a fixed tubular contact, a movable tubular contact, a resistance insertion device when it is only closed, the insertion devices and the resistance being arranged in a coaxial envelope, said device being controlled by the movable contact of the circuit breaker characterized in that the insertion device (19) is of the semi-mobile type and comprises a first means (51, 52) damping its closing and a second means (50, 44) delaying its opening when opening the circuit breaker. 2 / A circuit breaker according to claim 1, characterized in that the first means (51, 52) and the second means (50, 44) are of the vacuum operating type. 3 / Circuit breaker according to one of claims 1 and 2, characterized in that the first means (51, 52) comprises a means for adjusting (53) the spacing between a semi movable insertion contact (20) of the device insertion (19) and a movable insertion contact (62) of the movable contact, said insertion device being subjected to the antagonistic action of a spring (55) acting in the direction of opening. 4 / Circuit breaker according to one of claims 1 to 3, characterized in that the spark arrester contact (29) is subject to the fixed contact by means of a support (23) with three radial arms (60) in the 'interval of which are arranged three beams (61) supporting the semi-movable insertion contact (20). 5 / Circuit breaker according to one of claims 1 to 5, characterized in that the resistor is constituted by a central battery (8) arranged in series with several peripheral batteries (92) connected in parallel. 6 / A circuit breaker according to claim 6, characterized in that the linear resistance of all the peripheral batteries (92) is equal to that of the central battery (8).